Production of solid olefin polymers in the presence of acetylenic compounds using alkyl titanium halide catalysts



United States Patent 3,022,283 PRODUCTION OF SOLID OLEFIN POLYMERS IN THE PRESENCE OF ACETYLENIC COMPOUNDS USING ALKYL TITANIUM HALIDE CATALYSTS John E. Wicklatz and Boris Franzus, Bartlesville, Okla,

assignors to Phillips Petroleum Company, a corporation of Delaware No Drawing. Filed June 18, 1959, Ser. No. 821,105

9 Claims. (Cl. 26t)93 .7)

This invention relates to the production of solid olefin polymers. In one aspect, the invention relates to an improved method for preparing from certain selected olefins solid polymers having a high isotactic content.

The application is a continuation-in-part of our copending US. patent application Serial No. 769,558, now abandoned, filed on October 25, 1958.

Various reactions for polymerizing olefins are described in the literature, and the polymerizations are generally carried out in the presence of catalysts. One type of catalyst which has recently been disclosed for use in the polymerization of monoolefins, particularly ethylene, consists of an organometal compound, e.g., triethylaluminum, and a compound of a heavy metal, e.g., titanium tetrachloride. It has been found that when certain olefins, e.g., propylene, are contacted with such a catalyst, a polymer is obtained which contains greater or lesser quantities of a fraction which is crystalline and which is characterized by certain regularity of molecular structure. Thus, a polypropylene molecule can be considered as a chain of Z-carbon units with a methyl side group attached to every other carbon atom in the chain. Certain polymers of this type as characterized by the fact that they contain series of such monomer units in which all the methyl side groups are oriented in space at the same position or at the same angle wtih respect to the respective tertiary carbon atoms to which they are attached. The portion of the polymer having this regular structure is highly crystalline and is generally referred to as isotactic polypropylene. The amount of isotactic polypropylene contained in the total polymer product formed in any given polymerization appears to have a significant influence on certain properties of the polymer product, such as hardness, modulus, ultimate tensile strength, range of melting temperatures, and molding and fiber forming properties. The higher the isotactic content of the polymer the more outstanding are the physical properties of that polymer.

It is an object of this invention, therefore, to provide an improved process for producing isotactic polymers.

Another object of the invention is to provide a process for preparing polymers having isotactic contents which are higher than those of conventionally prepared polymers.

A further object of the invention is to provide a process in which increased yields of isotactic polymers are obtained.

Other and further objects and advantages of the invention will become apparent to those skilled in the art upon consideration of the accompanying disclosure.

The present invention resides in the discovery that certain olefin polymers of very high isotactic content can be prepared if the polymerization is carried out in the presence of very small amounts of certain acetylenic compounds. Broadly speaking, in a process in which an olefin corresponding to the formula RCH=CH wherein R is an alkyl radical containing from 1 to 4 carbon atoms or a phenyl or alkyl substituted phenyl radical, is polymerized in the presence of a catalyst comprising a trialkylaluminum and a halide of titanium, the instant invention resides in the improvement of conducting the polymerization in the presence of an acetylenic compound of the formula R'-.CECR', wherein R is an alkyl, phenyl, biphenyl, alkyl substituted phenyl, or alkyl substituted biphenyl. When proceeding in accordance with the present invention, it has been found that polymers having isotaotic contents in the range of to percent and higher can be readily prepared. In contrast, if the polymerization is conducted in the absence of the acetylenic compound with a conventional catalyst, such as titanium trichloride and triisobutylaluminum, the isotactic content of the polymer product is usually less than 80 percent. The reason for the unexpected improvement obtained by employing the acetylenic compounds in the process of this invention is not completely understood. Furthermore, the results obtained are even more surprising when it is noted that only very small amounts of the acetylenic compounds are added during the polymerizations. In general, the addition of the acetylenic compounds to a polymerization system containing catalyst and an olefin, as herein described, makes it possible to obtain a polymer product having a higher isotactic content than that obtainable in the absence of such compounds.

t The olefins which are polymerized in accordance with the present process correspond to the formula RCH= CH wherein R is selected from the group consisting of an alkyl radical containing from 1 to 4, inclusive, carbon atoms, a phenyl radical and an alkyl-substituted phenyl radical. The total number of carbon atoms in the alkyl groups substituted on the phenyl ring does not exceed 6 carbon atoms. Examples of suitable olefins include propylene, l-bultene, l-pentene, 3-methyl-l butene, 3- methyl-l-pentene, 4-methyl-1-pentene, 3,3-dimethyl-'1- butene, styrene, Z-methylstyrene, 4-methyl-styrene, 3 ethylstyrene, 2-ethyl-3-methylstyrene, 3,5-diethylstyrene, 2,4-di-n-propylstyrene, and the like. It is often preferred to employ propylene as the monomer.

The polymerization process of this invention is conducted in the presence of a catalyst comprising trialkylaluminum and a halide of titanium. The trialkylaluminum can be represented by the general formula R" Al, wherein R" is an alkyl radical, preferably containing from 1 to 12, inclusive, carbon atoms. Examples of compounds corresponding to the'aforernen tioned formula which can be used include trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n butylaluminum, tri n pentylaluminum, triisooctyla=lu minum, tri-n-dodecylaluminum, and the like.

In addition to the trialkylalurninum, the catalyst used in the practice of this invention includes a halide of titanium. While any of the titanium halides can be used, including the chlorides, fluorides, bromides, and iodides, it is preferred to employ the triand tetrachlo rides of titanium. It has also been found to be particularly desirable to use titanium trichloride as a component of the catalyst system.

Specificexamples of catalyst systems which can be advantageously used include the following: triethylaluminum and titanium trichloride; triisobutylaluminum and titanium trichloride; tri-n-dodecylaluminum and titanium trichloride; titanium tribromide and tri-n butylaluminum; titanium tribrornide and triisooctylaluminum; titanium triiodide and tri-n-pentylaluminum; titanium triiodide and tri-n-hexylaluminum; titanium tetrachloride and triisobutylaluminum; titanium tetrabromide and tri-n'heptylaluminum; and titanium tetraiodide and triethylaluminum.

The acetylenic compounds, in the presence of which the polymerization is conducted, correspond to the formula R-'CEC in which R is selected from the group consisting of alkyl, phenyl, biphenyl, and alkyl-substi-tuted phenyl and alkyl substituted biphenyl radicals, each of the hydrocarbon radicals containing from 1 to 16 carbon atoms. It is to be understood from the foregoing that the Rs in the formula can be alike or ditferent. Examples of acetylenic compounds which can be employed include diphenylacetylene, dimethylacetylene, diethylacetylene, n-propylacetylene, methylethylacetylene, n-butylacetylene, methyl-n-propylacetylene, n-hexylacetylene, methyl-n-amylacetylene, ethyl-n-butylacetylene, n-octylacetylene, di-n-butylacetylene, methyl-n-hexadecylacetylene, n-hexadecylacetylene, tert-dodecylacetylene, ethyl(4 methylphenyl) acetylene, isopropyl( 3-methyl-2-biphenyl) acetylene, dipropylacetylene, di(4-methylphenyl)acetylene, di-tert-butylacetylene, dioctylacetylene, di(3-octylphenyDacetylene, didodecylacetylene, dihexadecylacetylene, di(2-biphenyl)acetylene, di(4-biphenyl)acetylene, di( 3-methy1-2-biphenyl) acetylene, di (4-tert-decylphenyl) acetylene, and the like.

The ratios of the catlyst components employed in the present process can be varied rather widely, depending upon the particular monomer used and the operating con ditions. The mol ratio of the trialkylaluminurn to the titam'um halide is usually in the range of 1:1 to 10:1 with a preferred range being 2:1 to 5:1. The concentration of catalyst in the polymerization zone is usually in the range of 0.01 to 5.0 weight percent, based on the monomer charged to that zone, although larger amounts can be used.

It has been discovered that only very small amounts of the acetylenic compounds are required in order to obtain the improvement according to the present invention. The amount of the acetylenic compound employed is generally in the range from 0.01 to 0.5 mol, preferably from 0.01 to 0.3 mol, per mol of the total catalyst composition. The amount of the acetylenic compound utilized is also limited by the amount of the monomer charged to the polymerization zone. Thus, from 0.001 to 0.10, preferably from 0.005 to 0.06, weight percent of the acetylenic compound is employed in the polymerization, the aforementioned values being based upon the amount of monomer charged to the polymerization zone. In order to obtain maximum yields of isotactic polymer, it is important that the amounts of the acetylenic compounds added do not exceed the specified ranges.

The process of this invention is usually carried out in the presence of a hydrocarbon diluent which is relatively inert and liquid under the conditions of the process and does not have a deleterious efiect on the catalyst. Suitable diluents include paraflinic, cycloparafiinic and/or aromatic hydrocarbons. Examples of such diluents in clude propane, butane, pentane, hexane, cyclohexane, methylcyclohexane, benzene, toluene, the xylenes, and the like. The relative amounts of diluent and olefin employed in the polymerization depend upon the particular conditions and techniques used and are generally governed by the capacity of the apparatus to effect suitable agitation and heat removal. In general, the total olefin content of the feed mixture charged to the polymerization reactor is in the range of 0.5 to 25 weight percent, of the diluent present in the reactor.

The polymerization can be carried out at a temperature varying over a rather broad range, for example, from zero to 500 F. However it is usually preferred to conduct the reaction at a temperature in the range of 100 to 350 F., and more desirably between 200 and 300 F. The pressure employed in the process can vary from atmos pheric and below to about 400 to 500 psig or higher. In general, pressures are satisfactory which are sufficient to maintain the reaction mixture substantially in l' uid phase.

been found that various materials in some inf e a tendency to inactivate the catalyst f ption. These materials include ater- Therefore, it is usually desirable to free the olefins to be polymerized from these materials, as well as from other materials which may tend to inactivate the catalyst before contacting the olefin with the catalyst. Any of the known means for removing such contaminants can be employed. Furthermore, the hydrocarbon diluent employed in the process should also be freed of contaminants, such as water, oxygen, and the like. It is desirable also that air and moisture be removed from the reaction vessel before the reaction is carried out. This is usually accomplished by purging with an inert gas as described more in detail hereinafter. In some cases, small amounts of catalysts inactivating materials, such as oxygen and water, can be tolerated in the reaction mixture while still obtaining reasonably good polymerization rates. It is to be understood, however, that the amount of such materials present in the reaction mixture shall not be sufficient to completely inactivate the catalyst.

The process of this invention can be carried out as a batch process by pressuring the olefin to be polymerized into a reactor containing the catalyst, the acetylenic compound, and the diluent. When employing a catalyst comprising a trialkylalurninum and titanium trichloride, it is preferred to add a portion of the diluent initially after which this material is purged with an inert gas such as nitrogen. The catalyst components are then charged separately to the reactor with intermediate purging and with the trialkylaluminum being added in at least a portion of the remainder of the diluent. Any diluent remaining can then be introduced into the reactor after which the -m0nomer is added to the reactor. Thereafter, the reactor is heated until polymerization is initiated. If the acetylenic compound is suihciently high boiling so that it will not be removed during purging operations, it can be added to the reactor with the initial diluent. It can also be charged after addition of the catalyst components or at any other suitable time, preferably prior to the addition of the monomer. i-f low boiling acetylenic compounds, such as acetylene and dimethylacetylene, are employed, such compounds should be added subsequent to all purging operations and preferably prior to the addition of the monomer. If desired, the acetylenic compound can be added immediately prior to the addition of the monomer, and in some instances it may be added with the initial monomer charge. While it is preferred to operate in accordance with the aforementioned charging procedure, it is to be understood that it is not intended to limit the invention to any particular method for adding the reactant materials to the reactor. Furthermore, the process can be carried out continuously by maintaining the above-described concentration of reactants in the reactor for a suitable residence time. The residence time used in a continuous process can vary widely, since it depends to a great extent upon the temperature at which the process is carried out and upon the specific olefin that is to be polymerized. However, the residence time in a continuous process generally falls within the range of one second to an hour or more. In a batch process, the time for the reaction can also vary widely, such as from 15 minutes up to 24 hours or more.

Upon the completion of the polymerization reaction, any excess olefin is vented and the contents of the reactor are then treated by any suitable method to inactivate the catalyst and remove the catalyst residues. In one method, inactivation of the catalyst is accomplished by washing with an alcohol, water or other suitable materials. In some cases, the catalyst inactivating treatment also removes a major proportion of the catalyst residues while in other cases it may be necessary to treat the polymer with an acid, a base or other suitable material to effect the desired removal of the catalyst residues. The treatment of the polymer may be carried out in a comminution zone, such as a Waring Blendor, so that a finely divided, polymer is thereby provided. The polymer is then sepa-- rated from the diluent, e.g., by decantation, filtration, or other suitable method, after which the polymer is dried,

v The diluent and treating agents can be separated by any suitable means, e.g., by fractional distillation, and reused in the process.

A more complete understanding of the invention can be obtained by referring to the following illustrative examples which are not intended, however, to-be unduly ,limitative of the invention.

EXAMPLE I A series of runs was carried out according to this invention in which propylene was polymerized with a catalyst consisting of triethylaluminurn and titanium trichloride in the presence of an acetylenic compound.

In run 1 shown in the table hereinafter, 1000 ml. of cyclohexane was charged to a stainless steel reactor. After purging this material with nitrogen, 0.674 gram of titanium trichloride was added to the reactor. The reactor was then closed and flushed twice with nitrogen. There was then added to the charging tube of the reactor 1.49 grams of triethylaluminum in 300 ml. of cycloheXane. The reactor stirrer was started and allowed to run for one minute. Thereafter, 0.1 gram of diphenylacetylene dissolved in 300 ml. cyclohexane was introduced into the reactor through the charging tube, and the tube was rinsed by adding an additional 400 ml. of cyclohexane. The reactor wa then flushed twice at 100 p.s.i.g. with propylene, and the reactor stirrer was started, after which 0.6 pound (272 grams) of propylene was charged. The reactor was heated until polymeriza. tion wasinitiated, and the temperature was maintained in the range specified in Table I'hereinafter. Additional propylene was bled into the reactor during the latter part of the run. At the, end of the reaction period, the propylene feed was shut 011, the stirrer was stopped, and the reactor was cooled. A total of 1.17 pounds (530 grams) of propylene was charged to thereactor during the run.

Runs 2 to 5 shown in the table were conducted in a manner similar to run 1 except that the acetylenic compound was added to the reactor in the initial diluent charge (1000 ml. of cyclohexane) and the organoaluminum compound was charged in 500 ml. of diluent through the reactor charging tube. Five hundred ml. of cyclohexane was then added as a rinse through the charging tube.

In runs 6 and 7,-in which dimethylacetylene and acetylene were used, the charging procedure of 'run 1 was varied by introducing the acetyienic compounds into the charge line from a bomb after the propylene purge of the reactor had been accomplished. The materials then entered the reactor ahead of the propylene monomer charge.

Upon the completion of each run, the reactor was opened, and the contents thereof were discharged into about an equal volume of isopropyl alcohol. This mixture was then transferred to a Waring ,Blendor where it was comminuted at high speed for about 1 minute. The polymer, which then filtered from the mixture, was dried in a vacuum oven at 80 C.

The isotactic content of each of the polymer products was determined by placing 2510.1 grams of polymer in a weighed extraction thimble and extracting with 100 ml. of n-heptane for 2.5 hours in an ASTM Rubber Extraction apparatus. The thimble was then removed and dried in a forced air oven at 110 C. for two'hours after which it was cooled in a desiccator and weighed. Two tests were run on each polymer product. The weight percent of residue based on the original polymer was calculated for each test and averaged and then recorded as the isotactic content of that particular polymer.

The conditions under which the various runs were below in Table I.

Table 1 Run No 1 2 3 4 5 6 8 1 Grams 0.674 0. 684 0.665 0.585 0.630 0.634 0.643 ER/Iillim0los..- 4.35 4. 43 4.32 3.80 4. 08 4.12 4.17 Grams 1. 49 1.51 1. 47 1.28 1.39 1.40 1. 43 Millimoles.- 13.0 13.2 12.9 11.2 12.2 12.29 12. 52 Acetylcnic corn- (0 N ne 0.1 0.2 0.3 0.340 0.085 0.055 Millimoles.- 0.56 1.12 1.68 1.91 1.03 1.02 Mol ratio, TEA/ 'liOl 3 0 2.98 2.98 2. 98 3.0 2. 99 3.0 Moles acetylenic compound per mol catalyst .0323 .0075 .0975 .1270 .0635 0.069 Temperature, F.:

ow 200 200 200 200 200 200 200 High- 260 255 260 1 275 240 300 260 Time, hours 2. 67 2.67 2.5 2.5 2.5 1.75 2.5 Propylene, grams- 530 500 635 527 658 353 470 Yield, grams 419 397 408 438 475 220 405 Iroductivity, gm;

gm. 0 193 181 219 235 235 116 196 Isotactic content,

percent 8G 87 92 86 82 1 Control run. 2 Diphenylacetylene. 3 Diethylacetylene. Dimethylacctyleue. 5 Time measurement started when temperature reached 200 13.

Tests were made to determine certain physical properties of the polymers obtained in runs 1, 2, 3, 4, 5 and 8. The results of these tests are set forth 'herembelow in Table II. Table 11 Run No 1 2 3 4. 5 8

Inherent vis- Insol. 4.23 Insol. Not dct. Not det. Insol.

cosity 0.60.4 .37 2-31 2. 34 5. 05 i .65 Density, g/cc.

at 23 0. 0.9054 0.9058 0.0055. 0.9136 0.0046 0.9032 Strength, IZOD,

ft. lbs/in notch 4 1.06 1.1 2. 4 1. 4 1.8 1. 2 Stiffness, p.s.i. l45,000 152,000 168,000 174,000 135, 000 124, 000 Tensile at yield,

psi. 5,120 5,208 5,058 4, 825 4,376 4, 070 Tensile at break,

psi. 5,125 5,208 3,198 3,053 2, 744 4, 070 Elongation at break, percent 5 18 20 40 38 55 29 Zero strength temperature, F. 330 305 336 300 324 280 Determined. by method of Kemp et 511., Ind. 8: Eng. Chem. 35,1108 (1943).

Determined by method of ASTINI D-1238-52T. Mod1fied by taking 5 samples at 2 minute intervals, averag ng the 5 values (weights), discarding any values Wh lCh deviate from the average by more than 5 percent by weight, reaveragmg and multiplying by 5 to obtain. the amount of polymer extruded in 10 minutes. The melt index is defined as the grams of polymer extruded in 10 minutes through an 0.0825 inch orifice at 190 C. when subjected to a load of 2,160 grams. In runs 3, 4. and 5, 10 times the normal load was used, the value given representing a high load melt index. I

The density values were obtained by the use of a density gradient column which was prepared according to the method of Tung and Taylor, J. Polymer Science, 17 441 (19 55), ibid 19, 598 (-1956), and ibid 21, 14411956). n preparing polypropylene samples for the tests, polymer from each run was molded into a slab in a mold'hcated at 420 F. When the polymer was molten, the mold was cooled to about room temperature at the rate of about F. per minute. Thereafter, the slab was removed from the mold, and a piece of the slab about the size of a pea was used in the density determination test. In this test, a tube having a length slightly over one meter and an inside diameter of 4 cm. is graduated into onernillimeter divisions. The tube is filled with a water-ethanol mixture, introduced in a manner such that the ratio of ethauol to water increases progressively from the bottom to the top. The density of the liquid contents is thus diminished uniformly up the tube. Hollow glass beads of known densities within the tangent the density gradient in the tube are introduced into the column and these beads settle to a point' where their density :is in equilibrium with that of the liquid. The positions of the beads are plotted against density on a graph. A sample of polypropylene, prepared as just described, is dropped in the column and after about 15 minutes, the sample comes to rest at a point where its weight is exactly equal to the weight of the displaced liquid. The position is noted and referred to the graph, from which the density can be determined with an accuracy within the limits of $0.0002 gm./cc. Since the tubes are operated at ambient temperature, it is necessary to plot the positions of the beads for each set of determinations.

Determined by method of ASTM D256-54T /4" bar).

Determined by method of ASIM D74750.

Determined by method of ASTM D-412-51T.

Essentially by method of Islyn Thomas, Injection Molding of Plastics, Rheinhold Pub. Corp., page 504 (1947).

2 7 Example 11 Another series of runs was carried out in which propylene was polymerized with a catalyst consisting of triethylaluminum and titanium trichloride in the presence It is apparent from an examination of the data included in Table III that the process of this invention results in the production of propylene polymers having isotactic contents in excess of 85 percent, e.g., up to of an ncetylenic compound 5 97 percent. It will be noted that in the control run in a I In this series of runs, the procedure of run 1 of which an acetylemc compolmd not used the Poly- Example I was followed except as noted hereinafter propylene product had an lsotactlc content of cent. In runs 11 to 22, the acetylenic compound was added to the reactor in the initial diluent charge (1000 ml. of The polyniqrs P "i accordance fi CW1 Ohexane) and the organoaluminum compound was tion have utility in applicatlons where so 1d p astlcs are 1 used. They can be molded to form articles of any dechargeo in 500 m1. of diluent through the reactor charg- I ing tube. Five hundred milliliters of cyclohcxane was Shape Such as bottes or contamels for lqul. then added as a rinse through the charging tube. Run Furthermqe they can formed mm Sheets film or Plpe 10 Was conducted in the same manner as runs 6 and 7 by faxtfuslon or other Smtable Pi l of Exa mp1 e I The control runs of Examples 1 and H 5 IL will be apparent to those stalled in the art that many i 6 runs 8 and were carried out in the manner of variations and modifications of the lnvenuon can be made .2 5 of Examle and runs 11 to 22 of Examplfi H upon study of the foregoing disclosure. Such variations except that the acetylenic compound was not included in and modlficatlons, are bfgheved to come wlthm 591m the initial diluent charge. Each of the polymer products and SCOP? of the mventlonwas recovered and its isotactic content determined as We clalm: described in Example I. 1. In a process for polymerizing an olefin 1n the The conditions under which the runs were conducted presence of a catalyst comprlsmg a trlalkylalummum and and the results of the runs are set forth below in atnhalide of titanium, the improvement which compnses Table III. contacting said catalyst with an olefin corresponding to Table III Run N0 9 10 11 12 13 14 15 TiCla! Grams 0.664 0007---.-- 0.009 0.579 0.614 0.676 0.626 ivlillimoles 4.30 3.92... 3.96-- 3.70-- 3.99-.- 4.39-.- 4.00. Grams 1.44 1.34 1.34-- 1.27-- 1.35-- 1.40.--- 1.37. Millimoles... 12.0..- 11.7-- .7 11.1.-- 11.8-- 13.0-- 12.0. Acetylenic compound Control.-. irnethyl Dlethyl Diethyl tu. 2-octyne 3-octyne 4-0ctync 2a" 22 1 1112005... M01 ratio, TEA/T1013 2.94 2.99.-- 2.96-.- 2.96.. 2.96.- 2.98 2.98. g doles aceztylenicrcompound per mol catalyst.-- 0.1 0.128 0.253 0.127.. 0.126.. 0.126

em era ure, a:

190W 200 200 200 200 900 200 200, High. 260 240 2 250 240 255, Time, hours 2.5--.- 2.5 2.5-- 2.5.. 2.5.. 2.5. Propylene, lbs 1.130 1.265 1.000 1.200 1.100 1.120 1.000. Yield, grams... 388 M2 274 210 150 237 238. Productivity, gin/gm. cat 18 68 140 117 79 109 119. lsotactic content, percent 79.5 97 89. 9 Q2 87.

Run No 10 17 18 19 20 21 22 Grams 0.626 0.686.. Millimoles.. 4.45... EA:

Grams.-. 1.52--.------ Millimoles.- 13.3.- Acetylenic compound 5-de0yne Gms 0280 0.014.- 0180 Milliruoles..- 4.45. Mol ratio, TEA/TiC 3.00. Moles acetylenic compound per mol catalyst-.- 0.250 Temperature, F.:

Low 20" Hi h 950 Time, hours 2.5.- Propylene, lh 1.100 Yield, grams 248 42 Productivity, gmjgm. cat 11% 98 11a 52 1o 82. Isotactic content, percent 05 86 85.5-. 90.4.- 93.0.- 87.3.

1 Control run.

2 Dimethylacetylene.

3 Diethylaoetylene.

4 Methyl-n-amylacetylene.

5 Ethyl-n-butylacetylene.

6 Di-n-propylacetylene.

From a consideration of the data in Table I, it is seen that in accordance with the instant invention propylene polymers having isotactic contents of 85 percent and higher were produced. When carrying out the polymerization with a similar catalyst but in the absence f he acetylenic compounds of this invention, the polydu t had a considerably lower isotactic content. 8% from the data in Table II that the poly- 2. .3.4 and 5, prepared according to a p ropreties which are supee, obtained in the control run.

1 Time measurement started when temperature reached 200 F.

8 Di-n-butylacetylene.

9 Methynl-propylacetylene.

n-Propylacetylene.

11 Methylethylacetylene.

Phenylacetylene.

the formula R-CH=CH wherein R is an alkyl radical containing from 1 to 4, inclusive, carbon atoms, said contacting occurring in the presence of an acetylenic compound corresponding to the formula R'--CEC--R, wherein R is selected from the group consisting of an alkyl radical and a phenyl radical, each said radicals containing from 1 to 16, inclusive, carbon atoms, the amount of said acetylenic compound being in the range of 0.01 to 0.5 mol per mol of said catalyst.

2. A process in accordance with claim 1 wherein said acetylenic compound is diphenylacetylene.

3. A process in accordance with claim 1 wherein said acetylenic compound is diethylacetylene.

4. A process in accordance with claim 1 wherein said acetylenic compound is di-n-butylacetylene.

5. In a process for polymerizing an olefin in the presence of a catalyst comprising a trialkylaluminnm and a trihalide of titanium, the improvement which comprises contacting said catalyst with an olefin corresponding to the formula R--CH=CH wherein R is an alkyl radical containing from 1 to 4, inclusive, carbon atoms, said contacting occurring in the presence of an acetylenic compound corresponding to the formula R'CEC-R', wherein R is selected from the group consisting of an alkyl radical and a phenyl radical, each said radicals containing from 1 to 16, inclusive, carbon atoms, and in the presence of a hydrocarbon diluent at a temperature in the range of zero to 500 F. and at a pressure sufficient to maintain said diluent in the liquid phase, the amount of said acetylenic compound being in the range of 0.01 to 0.5 mol per mol of said catalyst and in the range of 0.001 to 0.10 weight percent of said olefin.

6. The process according to claim 5 in which the amount of said acetylenic compound is in the range of 10 0.01 to 0.3 mol per mol of said catalyst and in the range of 0.005 to 0.06 weight percent of said olefin.

7. The process according to claim 5 in which said catalyst consists essentially of triethylaluminum and titanium trichloride.

8. The process according to claim 5 in which said catalyst consists essentially of triisobutyl'aluminum and titanium trichloride.

9. In a process for polymerizing propylene in the presence of a catalyst comprising triethylaluminum and titanium trichloride, the improvement which comprises contacting said catalyst with propylene in the presence of dimethylacetylene, the amount of said dimethylacetylene being in the range of 0.01 to 0.5 mol per mol of said catalyst.

References Cited in the file of this patent UNITED STATES PATENTS 2,898,327 McCullogh et al Aug. 4, 1959 FOREIGN PATENTS 536,899 Italy Dec. 12, 1955 

1. IN A PROCESS FOR POLYMERIZATION AN OLEFIN IN THE PRESENCE OF CATALYST COMPRISING A TRIALKYLALUMINUM AND A TRIHALIDE OF TITANIUM, THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID CATALYST WITH AN OLEFIN CORRESPONDING TO THE FORMULA R-CH=CH2, WHEREIN R IS AN ALKYL RADICAL CONTAINING FROM 1 TO 4, INCLUSIVE, CARBON ATOMS, SAID CONTACTING OCCURING IN THE PRESENCE OF AN ACETYLENIC COMPOUND CORRESPONDING TO THE FORMULA R''-C=C-R'', WHEREIN R'' IS SELECTED FROM THE GROUP CONSISTING OF AN ALKYL RADICAL AND A PHENYL RADICL, EACH SAID RADICALS CONTAINING FROM 1 TO 16, INCLUSIVE, CARBON ATOMS, THE AMOUNT OF SAID ACETYLENIC COMPOUND BEING IN THE RANGE OF 0.01 TO 0.5 MOL PER MOL OF SAID CATALYST. 